Wafer enhanced electrodeionization (WE-EDI) is a new technology that has been shown to removal ions from fermentation broths to very dilute levels (Arora et al., 2007). The novelty in the process is producing unique wafers, that transport ions, and incorporating these into an electrodialysis stack. Although the technology has been shown to be viable for dilute ion separations, areas such as selective separations, wafer enhancement, and ion exchange bead selection have not been explored. This paper is focused on the removal of sodium ion in the present of other competing ions such as potassium and calcium. The purpose is to produce low sodium juice for health purpose especially for low sodium tolerance patients. Using WE-EDI technology would allow controlling the selectivity of the ions. Moreover, WE-EDI will provide and attractive alternative to the use of bipolar membranes in electrodialysis. The WE-EDI technology has been shown to increase the performance of the membranes by increasing the transport of ions through the system. For instance, early studies of removal of sodium and potassium show up to a 40% reduction of power under certain conditions. WE-EDI also may increase the life time of the membrane especially in high complex media such as juice by allowing water dissociation on the surfaces of the resin beads instead of on the surface of the membranes, which is violent and hard on the surface layer.

This paper addresses the characteristics of wafer: porosity and capacity with different composition. We also propose a mathematical model that provides a good prediction for product quality, especially for low sodium juice production. The selectivity difference between sodium, potassium, and calcium will be evaluated in order to optimizing the process performance. The mathematical model based on the diffusion model of ions transport at the surface of the resins beads. The mathematical model will provide the fundamental understanding of ions transport in WE-EDI.